package string;

import java.util.HashMap;
import java.util.Map;

/** 72.Edit Distance 编辑距离
 *
 Given two words word1 and word2, find the minimum number of operations required to convert word1 to word2.

 You have the following 3 operations permitted on a word:

 Insert a character
 Delete a character
 Replace a character
 Example 1:

 Input: word1 = "horse", word2 = "ros"
 Output: 3
 Explanation:
 horse -> rorse (replace 'h' with 'r')
 rorse -> rose (remove 'r')
 rose -> ros (remove 'e')
 Example 2:

 Input: word1 = "intention", word2 = "execution"
 Output: 5
 Explanation:
 intention -> inention (remove 't')
 inention -> enention (replace 'i' with 'e')
 enention -> exention (replace 'n' with 'x')
 exention -> exection (replace 'n' with 'c')
 exection -> execution (insert 'u')
 */
public class Q72_EditDistance {

    private int minDistance(String word1, String word2) {
        int n1 = word1.length();
        int n2 = word2.length();
        int[][] dp = new int[n1 + 1][n2 + 1];
        // 第一行
        for (int j = 1; j <= n2; j++) dp[0][j] = dp[0][j - 1] + 1;
        // 第一列
        for (int i = 1; i <= n1; i++) dp[i][0] = dp[i - 1][0] + 1;

        for (int i = 1; i <= n1; i++) {
            for (int j = 1; j <= n2; j++) {
                if (word1.charAt(i - 1) == word2.charAt(j - 1)) dp[i][j] = dp[i - 1][j - 1];
                else dp[i][j] = Math.min(Math.min(dp[i - 1][j - 1], dp[i][j - 1]), dp[i - 1][j]) + 1;
            }
        }
        return dp[n1][n2];
    }
}

